1. Field of the Invention
This application relates generally to microelectro-mechanical devices, and more particularly, to microelectro-mechanical sensors for detecting chemicals in a gaseous environment.
2. Background Information
Microelectronic and microelectromechanical (MEMS) devices have been used in chemical sensors as discussed in H. Baltes, D. Lange, A. Koll, “The electronic nose in Lilliput,” IEEE Spectrum, September 1998, pp. 35-38, and in H. P. Lang, R. Berger, F. Battiston, J. P. Ramseyer, E. Meyer, C. Andreoli, J. Brugger, P. Vettiger, M. Despont, T. Mezzacasa, L. Scandella, H. J. Guntherodt, C. Gerber, J. K. Gimzewski, “A chemical sensor based on micromechanical cantilever array for the identification of gases and vapors”, Apply. Phys. A 66, pp. S61-S64, 1998.
A chemical sensor is a device that converts chemical information into an analytically useful signal, and chemical sensors are important for a variety of industrial and environmental applications, including the detection of hazardous chemicals, quality control in the food, perfume, and beverage industries, and medical applications.
Chemical sensors can include a sorbent layer deposited on an active area of a transducer, as described in R. A. McGill, M. H. Abraham, J. W. Grate, “Choosing polymer coatings for chemical sensors,” CHEMTECH 24, pp. 27-37, 1994. Conventional chemical sensors utilize transducers which are relatively large and have millimeter sized dimensions. See, for example, D. Diamond, Principles of Chemical and Biological Sensors, J. Wiley & Sons Inc. New York, 1998. Current state of the art chemical detectors are typically hand held systems.